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| author | Robert Jarzmik <robert.jarzmik@free.fr> | 2010-01-27 18:38:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-03-02 23:54:47 +0100 |
| commit | 5e23e90f33888769ffe253663cc5f3ea0bb6da49 (patch) | |
| tree | 9a59d36fdaaecea5eb7fa2d39c655032dc6920a2 /drivers/usb/gadget/pxa27x_udc.h | |
| parent | USB: serial: add support for serial port on the moschip 7715 (diff) | |
| download | linux-5e23e90f33888769ffe253663cc5f3ea0bb6da49.tar.xz linux-5e23e90f33888769ffe253663cc5f3ea0bb6da49.zip | |
USB: pxa27x_udc: Fix deadlocks on request queueing
As reported by Antonio, there are cases where the ep->lock
can be taken twice, triggering a deadlock.
The typical sequence is :
irq_handler
\
-> gadget.complete()
\
-> pxa27x_udc.pxa_ep_queue() : ep->lock is taken
\
-> gadget.complete()
\
-> pxa27x_udc.pxa_ep_queue() : ep->lock is taken
==> *deadlock*
The patch fixes this by :
- releasing the lock each time gadget.complete() is called
- adding a check in handle_ep() to detect a recursive call,
in which case the function becomes on no-op.
The patch is still not good enough for ep0. For this unique
endpoint, another well thought over patch will be needed.
Reported-by: Antonio Ospite <ospite@studenti.unina.it>
Tested-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/gadget/pxa27x_udc.h')
| -rw-r--r-- | drivers/usb/gadget/pxa27x_udc.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/usb/gadget/pxa27x_udc.h b/drivers/usb/gadget/pxa27x_udc.h index e25225e26586..ff61e4866e8a 100644 --- a/drivers/usb/gadget/pxa27x_udc.h +++ b/drivers/usb/gadget/pxa27x_udc.h @@ -318,6 +318,11 @@ struct udc_usb_ep { * @queue: requests queue * @lock: lock to pxa_ep data (queues and stats) * @enabled: true when endpoint enabled (not stopped by gadget layer) + * @in_handle_ep: number of recursions of handle_ep() function + * Prevents deadlocks or infinite recursions of types : + * irq->handle_ep()->req_done()->req.complete()->pxa_ep_queue()->handle_ep() + * or + * pxa_ep_queue()->handle_ep()->req_done()->req.complete()->pxa_ep_queue() * @idx: endpoint index (1 => epA, 2 => epB, ..., 24 => epX) * @name: endpoint name (for trace/debug purpose) * @dir_in: 1 if IN endpoint, 0 if OUT endpoint @@ -346,6 +351,7 @@ struct pxa_ep { spinlock_t lock; /* Protects this structure */ /* (queues, stats) */ unsigned enabled:1; + unsigned in_handle_ep:1; unsigned idx:5; char *name; |